Composite Delamination Growth

Delamination, the splitting or separating of individual plies of a laminated composite material, is a common mode of failure for composite structures. A proposed new ASTM International standard will aid in the prediction of delamination propagation.

The proposed new standard, WK30580, Guide for Development of Benchmark Solutions for Composite Delamination Growth Analysis, is being developed by Subcommittee D30.02 on Research and Mechanics, part of ASTM International Committee D30 on Composite Materials.

According to Ronald Krueger, associate research fellow, National Institute of Aerospace, the proposed guide will include several benchmark solutions (reference solutions to which other solutions will be compared) for delamination onset and growth in composite coupons that are representative of what would occur in composite structures.

“Having the ability to predict delamination propagation, onset and growth in the commercial finite element codes used by industry to design and certify composite structures will enable the use of analyses to reduce the amount of subcomponent testing now required in the building block approach for certification of damage-tolerant composite structures,” says Krueger.

Krueger notes that, by using a combination of testing and analyses rather than testing alone, designs will be developed faster and less expensively, and certified more quickly, than is currently possible.

“WK30580 will also describe an approach that users can follow to develop their own benchmark solutions,” says Krueger. “Once developed, these benchmark solutions may be used by finite element code developers to check their implementation or by code end-users to calibrate the numerical input parameters required to obtain the correct results. Once the parameters have been identified, they may then be used with confidence to model delamination growth for more complex configurations.”

Interested parties are welcome to join in the development of WK30580. Krueger says that D30.02 is seeking experts with knowledge and experience in finite element analysis, code development, benchmarking, code validation and verification, fracture mechanics and composites.